{ "spore": "profile", "id": "gold-alloys", "spore_version": "0.2", "family": "precious-metals", "name": "Gold alloys", "abbreviation": "Au alloys", "role": "electrical contact and microconnector metal, brazing filler, and jewellery alloy", "category": "metals", "type": "precious-metals", "summary": "Gold is alloyed with nickel, palladium, silver, iron and antimony to change its strength, melting point and electrical behaviour. The best-documented grade in this file, Au82/Ni18, melts at 955 degC, has an electrical resistivity of 15.5 microohm cm and a tensile strength of 616 MPa as a rolled foil. A brazing filler of the same composition is specified at 949 degC solidus-liquidus. Au75/Pd25 foil melts at 1410 degC. An Au-Fe alloy with 0.07 at% iron is used as a thermocouple element down to very low temperatures (NBS, 1972).\n", "best_for": "Contacts, microconnectors and brazes that must resist oxidation and sulphur attack in a small volume (supplier statements for Au-Ni and Au-Pd)", "weakest_at": "Strength and hardness are set by the alloy and temper, and most alloys here have only supplier figures; Au-Ag and Au-Sb have almost no property data in this file", "identity": { "formula": "Au82/Ni18 (gold 82, nickel 18, as listed); binary family Au-Ni, Au-Pd, Au-Ag, Au-Fe and Au-Sb", "designations": [ { "system": "AMS", "code": "AMS4787", "note": "brazing filler metal, 82Au-18Ni, 1740 F solidus-liquidus; revision C", "source": "ams4787c", "where": "Title of the specification" } ], "source": "goodfellow-au82ni18", "where": "Product page, composition line (Au 82/Ni 18); Au75/Pd25 composition from goodfellow-au75pd25; Au-Fe concentrations from sparks1972 (Au-0.02 at% Fe and Au-0.07 at% Fe)" }, "tags": { "environments": [], "stresses": [ "extreme-cold" ], "applications": [ "electronics-and-chips", "thermal-control" ] }, "properties": [ { "benchmark": "density", "label": "Density, Au82/Ni18 foil", "value": 15.8, "bound": "exact", "unit": "g/cm3", "scope": "material", "conditions": { "composition": "Au 82 / Ni 18 as listed", "form": "foil, film or sheet, as rolled", "temperature": "not stated" }, "method": "Physical property printed on the supplier product page", "status": "ground", "source": "goodfellow-au82ni18", "where": "Product page, Physical block, Density", "source_detail": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "melting_point", "label": "Melting point, Au82/Ni18", "value": 955, "bound": "exact", "unit": "degC", "scope": "material", "conditions": { "composition": "Au 82 / Ni 18 as listed", "form": "foil, as rolled", "note": "single value printed, no range" }, "method": "Thermal property printed on the supplier product page", "status": "ground", "source": "goodfellow-au82ni18", "where": "Product page, Thermal block, Melting point", "source_detail": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "melting_point", "label": "Solidus-liquidus temperature, 82Au-18Ni brazing filler", "value": 949, "bound": "exact", "unit": "degC", "scope": "material", "conditions": { "composition": "82Au-18Ni", "basis": "specification title gives 1740 F (949 degC)", "revision": "AMS4787 revision C, dated 4/1/1990" }, "method": "Value printed in the title of the SAE specification", "status": "ground", "note": "The specification title gives 1740 F (949 degC). A later revision of the specification exists (per a search result, not read here), so check the current revision before quoting this value.", "source": "ams4787c", "where": "Title of AMS4787C; Scope", "source_detail": { "title": "AMS4787C: Brazing filler metal, high temperature 82Au-18Ni, 1740 F (949 C) solidus-liquidus temperature", "id": "SAE AMS4787 revision C, dated 4/1/1990", "url": "https://saemobilus.sae.org/content/AMS4787C", "year": 1990, "kind": "standard", "license": "SAE International, title and scope read, text not reproduced" } }, { "benchmark": "electrical_resistivity", "label": "Electrical resistivity, Au82/Ni18 foil", "value": 15.5, "bound": "exact", "unit": "microohm cm", "scope": "material", "conditions": { "composition": "Au 82 / Ni 18 as listed", "form": "foil, as rolled", "temperature": "not stated" }, "method": "Electrical property printed on the supplier product page", "status": "ground", "source": "goodfellow-au82ni18", "where": "Product page, Electrical block, Electrical resistivity", "source_detail": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, Au82/Ni18 foil", "value": 49, "bound": "exact", "unit": "W/(m K)", "scope": "material", "conditions": { "composition": "Au 82 / Ni 18 as listed", "temperature": "23 degC" }, "method": "Thermal property printed on the supplier product page, value at 23 degC", "status": "ground", "note": "The supplier material-information page describes the alloy as having a thermal conductivity of approximately 150 W/(m K) without a table. The product page value of 49 at 23 degC is used here; the two supplier pages disagree.", "source": "goodfellow-au82ni18", "where": "Product page, Thermal block, Thermal conductivity, 49 at 23 degC", "source_detail": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "cte", "label": "Coefficient of thermal expansion, Au82/Ni18", "value": 14, "bound": "exact", "unit": "ppm/K", "scope": "material", "conditions": { "composition": "Au 82 / Ni 18 as listed", "temperature_range": "20 to 700 degC" }, "method": "Printed by the supplier as x10-6 K-1, which is the same unit as ppm/K; no numeric conversion made", "status": "ground", "source": "goodfellow-au82ni18", "where": "Product page, Thermal block, Coefficient of thermal expansion", "source_detail": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "youngs_modulus", "label": "Modulus of elasticity, Au82/Ni18 foil", "value": 112, "bound": "exact", "unit": "GPa", "scope": "material", "conditions": { "composition": "Au 82 / Ni 18 as listed", "form": "foil, as rolled" }, "method": "Mechanical property printed on the supplier product page", "status": "ground", "source": "goodfellow-au82ni18", "where": "Product page, Mechanical block, Modulus of elasticity", "source_detail": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Tensile strength, Au82/Ni18 foil", "value": 616, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "composition": "Au 82 / Ni 18 as listed", "form": "foil, as rolled", "test_standard": "not stated" }, "method": "Mechanical property printed on the supplier product page", "status": "ground", "source": "goodfellow-au82ni18", "where": "Product page, Mechanical block, Tensile strength", "source_detail": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "elongation", "label": "Elongation at break, Au82/Ni18 foil", "value": 13, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "composition": "Au 82 / Ni 18 as listed", "form": "foil, as rolled", "test_standard": "not stated" }, "method": "Mechanical property printed on the supplier product page", "status": "ground", "source": "goodfellow-au82ni18", "where": "Product page, Mechanical block, Elongation at break", "source_detail": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "melting_point", "label": "Melting point, Au75/Pd25 foil", "value": 1410, "bound": "exact", "unit": "degC", "scope": "material", "conditions": { "composition": "Au 75 / Pd 25", "form": "foil, 0.2 mm thick, as rolled" }, "method": "Thermal property printed on the supplier product page", "status": "ground", "source": "goodfellow-au75pd25", "where": "Product page, Thermal block, Melting point", "source_detail": { "title": "Goodfellow: Gold-Palladium alloy foil (Au75/Pd25) product page", "id": "Goodfellow product page, Au 75 / Pd 25, 0.2 mm foil", "url": "https://www.goodfellow.com/usa/gold-palladium-alloy-foil-au75-pd25-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "density", "label": "Density, Au75/Pd25 foil", "value": 16, "bound": "exact", "unit": "g/cm3", "scope": "material", "conditions": { "composition": "Au 75 / Pd 25", "form": "foil, 0.2 mm thick, as rolled" }, "method": "Physical property printed on the supplier product page, printed without decimals", "status": "ground", "note": "The page prints 16 with no decimals, so the value is likely rounded.", "source": "goodfellow-au75pd25", "where": "Product page, Physical block, Density", "source_detail": { "title": "Goodfellow: Gold-Palladium alloy foil (Au75/Pd25) product page", "id": "Goodfellow product page, Au 75 / Pd 25, 0.2 mm foil", "url": "https://www.goodfellow.com/usa/gold-palladium-alloy-foil-au75-pd25-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" } }, { "benchmark": "melting_point", "label": "Eutectic temperature, Au-Sb (24.8 wt% Sb)", "value": 633, "bound": "exact", "unit": "K", "scope": "material", "conditions": { "composition": "Sb 24.8 wt%, gold remainder", "basis": "gold binary eutectic alloy row in the table" }, "method": "Table of gold binary eutectic alloys; the row prints 633 K and 680 F (633 K is 360 degC)", "status": "ground", "note": "The table lists the value only in kelvin. No Au-Sb density, resistivity or hardness was found in a page read in this run.", "source": "engtoolbox-gold", "where": "Table, row Sb - Antimony (Stibium), Melting point (K)", "source_detail": { "title": "Engineering ToolBox: Gold binary eutectic alloys and melting points", "id": "Engineering ToolBox, gold alloys melting points table (cited 2008 on page)", "url": "https://www.engineeringtoolbox.com/gold-alloys-melting-points-d_1434.html", "year": 2008, "kind": "web", "license": "web page, linked not reproduced" } }, { "benchmark": "seebeck_coefficient", "label": "Seebeck coefficient, KP versus Au-0.07 at% Fe thermocouple at 20 K", "value": 16.966, "bound": "exact", "unit": "microV/K", "scope": "material", "conditions": { "pair": "KP versus Au-0.07 at% Fe, pair output, not the alloy alone", "temperature": "20 K", "wire_diameters": "0.127 mm, 0.152 mm and 0.254 mm (Table 1)" }, "method": "Value printed in a table of the NBS paper for one thermocouple pair", "status": "ground", "note": "Seebeck coefficient is not in spores/property-canon.yaml, so this uses a short snake_case name. The same paper gives a low-temperature maximum of 16.82 microV/K at 17.9 K for the same pair.", "source": "sparks1972", "where": "Table 5 (KP versus Au-0.07 at% Fe at 20 K); Table 3 for the low-temperature maximum", "source_detail": { "title": "Low Temperature Thermocouples: KP, normal silver and copper versus Au-0.02 at% Fe and Au-0.07 at% Fe", "id": "Sparks, L. L., J. Res. Natl. Bur. Stand. A 76A(3), 263-283, doi 10.6028/jres.076A.029", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6706574", "year": 1972, "kind": "paper", "license": "public domain (NBS)" } } ], "corrosion": [ { "environment": "Air and high-temperature oxidation (Au-Ni, supplier statements only)", "headline": "Supplier says Au-Ni resists oxidation and corrosion; no test data were read.", "effect": "The Goodfellow material page describes Au-Ni as having exceptional corrosion resistance and as resistant to oxidation, and says a trace of platinum and yttrium improves sulfurization resistance. It gives no test conditions, times or measured rates.", "rating": "low", "conditions": { "basis": "supplier statements without test data", "composition": "Au82/Ni18 family" }, "source": "goodfellow-aunimaterial", "where": "Lead paragraph; Material Overview" }, { "environment": "Sulfur-bearing atmospheres (Au-Ni)", "headline": "Sulfurization resistance is claimed through trace platinum and yttrium additions; no rate was read.", "effect": "The supplier page says Au-Ni alloys gain sulfurization resistance from trace additions of platinum and yttrium, which lengthen component life in harsh environments. The page gives no exposure data.", "rating": "unknown", "conditions": { "basis": "supplier claim for alloys with trace additions; plain Au82/Ni18 not tested here" }, "source": "goodfellow-aunimaterial", "where": "Material Overview, sulfurization sentence" }, { "environment": "Corrosive and high-vacuum aerospace environments (Au-Pd, supplier statements only)", "headline": "Supplier describes the Au-Pd foil as combining gold's corrosion resistance with palladium's hardness.", "effect": "Goodfellow says the Au75/Pd25 foil merges the corrosion resistance and conductivity of gold with the hardness and wear resistance of palladium, and it lists corrosion-resistant aerospace components as an application. No corrosion test is quoted.", "rating": "low", "conditions": { "basis": "supplier product description without test data", "composition": "Au 75 / Pd 25" }, "source": "goodfellow-au75pd25", "where": "Product description; Applications" }, { "environment": "Au-Fe thermocouple use at cryogenic temperatures", "headline": "No corrosion test was read; the NBS paper reports the alloys as metallurgically stable.", "effect": "Sparks (NBS, 1972) calls the Au-Fe alloys metallurgically stable and says heat treatment matters for their thermopower. Corrosion and oxidation were not studied in the paper.", "rating": "unknown", "conditions": { "basis": "statement on metallurgical stability; no corrosion test", "temperature_range": "5 to 280 K in the paper" }, "source": "sparks1972", "where": "Introduction and Results" }, { "environment": "Not read (Au-Ag and Au-Sb)", "headline": "No corrosion data for these two alloy systems were read in this run.", "effect": "The Wikipedia electrum article gives the composition range and the natural occurrence of Au-Ag, but it does not discuss corrosion. Au-Sb corrosion was not found.", "rating": "unknown", "conditions": { "basis": "composition and occurrence only" }, "source": "wiki-electrum", "where": "Lead paragraph; Natural occurrence" } ], "risks": { "hazards": [ { "text": "Nickel, the second metal in Au-Ni and in white gold, is a skin sensitiser. PubChem lists the H317 allergic-skin-reaction statement in 99.9% of company reports and the H351 suspected-cancer statement in 72.9%.", "ghs": [ "H317", "H351" ], "source": "pubchem-nickel", "where": "Safety and Hazards, GHS Classification (CID 935)" }, { "text": "Pure gold does not meet GHS hazard criteria in 99.2% (502 of 506) of company reports on PubChem. No GHS classification was read for the Au-Pd, Au-Ag, Au-Fe or Au-Sb alloys.", "ghs": [], "source": "pubchem-gold-ghs", "where": "GHS Classification (CID 23985)" } ], "failure_risks": [ { "mode": "Output scatter between thermocouple wires", "trigger": "Au-Fe wire from different melts, or wire in a different annealing state", "consequence": "Sparks found wire-to-wire output differences of 2 to 4 percent typically and up to about 9 percent at 4 to 20 K. Heat treatment of Au-0.07 at% Fe was critical, and annealing raised the thermopower.", "severity": "moderate", "source": "sparks1972", "where": "Results, wire-to-wire comparison; Discussion of heat treatment" } ], "side_effects": [ { "text": "Nickel in white gold and Au-Ni can cause an allergic skin reaction when worn for long periods. Wikipedia notes that many countries do not use nickel in white gold.", "affects": "Skin of wearers sensitive to nickel", "source": "wiki-white-gold", "where": "Composition and nickel allergy sections" } ], "handling": [ { "text": "Sparks annealed one Au-Fe specimen at 350 degC for 20 minutes in air before testing. Annealing raised the thermopower, so the heat treatment must be recorded with each wire.", "source": "sparks1972", "where": "Specimen preparation; Results" }, { "text": "The Goodfellow foil is supplied as rolled, with a thickness of 0.2 mm for Au75/Pd25. Shape it as foil, because the supplier gives no hot-working data.", "source": "goodfellow-au75pd25", "where": "Product page, Form and Temper" } ], "mitigations": [ { "text": "Sparks states that the reference data can be adjusted with spot calibration on particular wires, which handles the wire-to-wire scatter.", "source": "sparks1972", "where": "Discussion of calibration" } ] }, "uses": [ { "application": "electronics-and-chips", "device": "High-reliability electrical contacts and microconnectors", "example": "Goodfellow says Au82/Ni18 is extensively used in high-reliability electrical contacts and brazing alloys, and that Au-Ni electrodeposited coatings are used in microconnectors and semiconductor devices.", "source": "goodfellow-aunimaterial", "where": "Applications and Advantages" }, { "application": "electronics-and-chips", "device": "Brazing filler for ceramics, steels and refractory metals in electronic packaging", "example": "The AMS4787 specification covers an 82Au-18Ni brazing filler in wire, rod, sheet, strip, foil, pig, powder, shot and chips. Goodfellow says the same alloy joins ceramics, steels and refractory metals in electronic packaging.", "source": "ams4787c", "where": "Scope; Goodfellow Applications and Advantages (goodfellow-aunimaterial)" }, { "application": "electronics-and-chips", "device": "Precision connector contacts and microelectronic bonding layers", "example": "Goodfellow lists precision connector contacts, bonding layers in microelectronics and corrosion-resistant aerospace components as uses of the Au75/Pd25 foil.", "source": "goodfellow-au75pd25", "where": "Applications" }, { "application": "thermal-control", "device": "Cryogenic thermocouple element (Au-Fe against KP or chromel)", "example": "NBS calls Au-Fe alloys the most promising thermoelement for very low temperatures. The paper measures the pair from 5 to 280 K and reports usable sensitivity below 4 K.", "source": "sparks1972", "where": "Introduction; Results (temperature range)" } ], "supply": [ { "subject": "Gold (base metal of every alloy in this file)", "abundance": "Consumption in 2025: jewelry 40%, electrical and electronics 7% (USGS, share of global consumption)", "producers": [ { "country": "China", "share_percent": 11.5, "year": 2025 }, { "country": "Russia", "share_percent": 9.4, "year": 2025 }, { "country": "Australia", "share_percent": 8.5, "year": 2025 }, { "country": "Canada", "share_percent": 6.1, "year": 2025 }, { "country": "United States", "share_percent": 4.8, "year": 2025 } ], "critical_lists": [ { "list": "Not checked in this run", "listed": false } ], "recycling": "USGS: about 90 tons of scrap were recycled in 2025, equal to about 60% of reported consumption.", "substitutes": [ "USGS: palladium, platinum and silver may substitute for gold; base metals clad with gold alloys economise on gold in electrical and electronic products." ], "source": "usgs-gold", "where": "World Mine Production table, 2025e (world total 3300 t; shares calculated by Space Mushroom); Consumption; Recycling; Substitutes" }, { "subject": "Nickel", "producers": [ { "country": "Indonesia", "share_percent": 66.7, "year": 2025 }, { "country": "Philippines", "share_percent": 6.9, "year": 2025 }, { "country": "Russia", "share_percent": 5.1, "year": 2025 }, { "country": "New Caledonia", "share_percent": 3.6, "year": 2025 }, { "country": "Canada", "share_percent": 3.6, "year": 2025 } ], "critical_lists": [ { "list": "Not checked in this run", "listed": false } ], "recycling": "USGS: nickel recovered from scrap was about 60% of apparent consumption in 2025, mostly as stainless-steel scrap.", "substitutes": [ "USGS: low-nickel, duplex and ultrahigh-chromium stainless steels substitute for austenitic grades in some uses." ], "source": "usgs-nickel", "where": "World Mine Production table, 2025e (world total 3900000 t; shares calculated by Space Mushroom); Recycling; Substitutes" }, { "subject": "Silver", "producers": [ { "country": "China", "share_percent": 13.1, "year": 2025 }, { "country": "Bolivia", "share_percent": 5.8, "year": 2025 }, { "country": "Chile", "share_percent": 5.4, "year": 2025 }, { "country": "United States", "share_percent": 4.2, "year": 2025 } ], "critical_lists": [ { "list": "USGS 2025 Final List of Critical Minerals (silver added in 2025)", "listed": true } ], "recycling": "USGS: about 1000 tons of silver was recovered from scrap in 2025, about 11% of apparent consumption.", "substitutes": [ "USGS: digital imaging, reduced-silver film and non-silver batteries substitute for silver in some uses; aluminum and rhodium may replace silver in others." ], "source": "usgs-silver", "where": "Introduction (critical-minerals list); World Mine Production table, 2025e (world total 26000 t; shares calculated by Space Mushroom); Recycling; Substitutes" }, { "subject": "Antimony", "producers": [ { "country": "China", "share_percent": 36.4, "year": 2025 }, { "country": "Bolivia", "share_percent": 4.5, "year": 2025 }, { "country": "Burma", "share_percent": 4.1, "year": 2025 }, { "country": "Australia", "share_percent": 1.2, "year": 2025 } ], "critical_lists": [ { "list": "Not checked in this run", "listed": false } ], "recycling": "USGS: most secondary antimony is recovered at secondary lead smelters as antimonial lead.", "substitutes": [ "USGS: chromium, tin, titanium, zinc and zirconium compounds substitute for antimony chemicals in enamels, paint and pigments." ], "source": "usgs-antimony", "where": "World Mine Production table, 2025e (world total 110000 t; shares calculated by Space Mushroom, listed countries only); Recycling; Substitutes" } ], "media": [], "documents": [ { "title": "Goodfellow Au82-Ni18 foil product page (gold-nickel foil, as rolled)", "type": "datasheet", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026 }, { "title": "Goodfellow: Gold-Nickel alloy material information", "type": "datasheet", "url": "https://www.goodfellow.com/usa/resources/gold-nickel-alloy-material-information/", "year": 2026 }, { "title": "Goodfellow Au75/Pd25 gold-palladium alloy foil product page", "type": "datasheet", "url": "https://www.goodfellow.com/usa/gold-palladium-alloy-foil-au75-pd25-group", "year": 2026 }, { "title": "AMS4787C brazing filler metal, high temperature 82Au-18Ni (SAE)", "type": "standard", "url": "https://saemobilus.sae.org/content/AMS4787C", "year": 1990 }, { "title": "Low Temperature Thermocouples: KP, normal silver and copper versus Au-0.02 at% Fe and Au-0.07 at% Fe (NBS, open access)", "type": "paper", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6706574", "year": 1972 }, { "title": "USGS Mineral Commodity Summaries 2026: Gold", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gold.pdf", "year": 2026 }, { "title": "USGS Mineral Commodity Summaries 2026: Nickel", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf", "year": 2026 }, { "title": "USGS Mineral Commodity Summaries 2026: Silver", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf", "year": 2026 }, { "title": "USGS Mineral Commodity Summaries 2026: Antimony", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-antimony.pdf", "year": 2026 }, { "title": "PubChem compound record Nickel (CID 935), GHS classification", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Nickel", "year": 2026 }, { "title": "PubChem compound record Gold (CID 23985), GHS classification", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/23985", "year": 2026 } ], "gaps": [ "Au-Ni contact grade hardness and conductivity (for example AuNi5): the Heraeus product pages returned 404 in this run, so no value was read.", "Au-Ag: no numeric property (density, melting range, resistivity, hardness) was read in a source this run. Wikipedia gives only the 20 to 80% gold range and the natural occurrence.", "Au-Sb: only the eutectic row (24.8 wt% Sb, 633 K) was read. No density, resistivity, hardness or corrosion data. Antimony GHS classification was not retrieved (PubChem antimony REST request failed).", "Au-Fe: only dilute compositions (Au-0.02 at% Fe and Au-0.07 at% Fe) were read; no commercial wire specification or density, melting point or tensile value was read.", "Palladium supply: the USGS Platinum-Group Metals chapter could not be retrieved (the PDF URL returned an HTML page), so no palladium producer shares are given.", "EU nickel release limits (REACH Annex XVII entry 27, EN 1811): the numeric limits were not read. The TUV page returned 403 and the EUR-Lex page was empty. Nickel release limits are therefore not quoted.", "Au-Ni or Au-Pd corrosion test data (salt spray, humidity, sulfur exposure): none found; the corrosion entries rest on supplier statements only.", "Jewellery grades (karat composition tables for gold alloys): only the Wikipedia white gold composition statements were read; no grade table was checked against a manufacturer page.", "Crystal structure and space group of the alloys: not read in this run.", "Au-Ag and Au-Pd wire or foil in a space application: no flight, vacuum or radiation result was found for these alloys.", "Au82/Ni18 thermal conductivity conflict: product page 49 W/(m K) at 23 degC against about 150 W/(m K) on the material-information page (no table).", "AMS4787 revision C (1990) was read; a later revision (H) exists per a search result that was not opened, so the current value may differ.", "The AWS BAu-4 designation was not checked against an AWS page and is left out of designations.", "Seebeck coefficient is not in property-canon.yaml; the benchmark name seebeck_coefficient is a short snake_case name used here.", "Pure gold reference values were not re-read for this file; see gold.yaml for those." ], "story": { "why": "Gold is alloyed with a second metal to change its strength, hardness or melting point. Au-Ni brazing filler is specified at 949 °C (1740 F) and is used to join ceramics, steels and refractory metals in electronic packaging. Au-Pd foil is described by the supplier as combining gold's corrosion resistance with palladium's hardness, for connectors. Au-Fe is used for thermocouples at very low temperature, where the NBS paper found its thermopower the best available. Au-Ag and Au-Sb are included as family members, but this file has little property data for them.", "uses": [ { "where": "Electronic contacts and microconnectors", "line": "Goodfellow describes Au82/Ni18 as used in high-reliability electrical contacts, and Au-Ni electrodeposited coatings are used in microconnectors and semiconductor devices." }, { "where": "Brazing in electronic packaging", "line": "The 82Au-18Ni brazing filler is specified by SAE AMS4787 for wire, rod, sheet, strip, foil, pig, powder, shot and chips. Goodfellow says it joins ceramics, steels and refractory metals in electronic packaging." }, { "where": "Precision connectors and aerospace parts", "line": "Goodfellow lists Au75/Pd25 foil for precision connector contacts, microelectronic bonding layers and corrosion-resistant aerospace components." }, { "where": "Cryogenic thermocouples", "line": "Sparks (NBS, 1972) measured Au-Fe against KP from 5 to 280 K and reported usable sensitivity below 4 K." } ], "can_do": [ { "label": "Contact metal", "line": "Au82/Ni18 foil has an electrical resistivity of 15.5 microohm cm as printed by the supplier. This is a single supplier figure and is not compared here with other contact materials.", "benchmark": "electrical_resistivity", "scope": "material", "value": "15.5 microohm cm" }, { "label": "Brazing", "line": "The 82Au-18Ni filler has a solidus-liquidus of 949 °C (1740 F). The Au-Pd foil has a melting point of 1410 °C.", "benchmark": "melting_point", "scope": "material", "value": "949 °C" }, { "label": "Strength", "line": "The rolled Au82/Ni18 foil reaches a tensile strength of 616 MPa with 13% elongation, reported by the supplier without a test standard.", "benchmark": "ultimate_tensile_strength", "scope": "material", "value": "616 MPa" }, { "label": "Low-temperature sensing", "line": "The NBS pair of KP against Au-0.07 at% Fe gives 16.966 microV/K at 20 K.", "benchmark": "seebeck_coefficient", "scope": "material", "value": "16.966 microV/K" } ], "compare": "The gold alloys in this file span a wide range of melting points. The Au-Ni brazing filler has a solidus-liquidus of 949 °C and the Au82/Ni18 foil melts at 955 °C, the Au-Sb eutectic is at 633 K, and the Au75/Pd25 foil melts at 1410 °C. The Au-Pd foil is slightly denser (16 g/cm3) than the Au82/Ni18 foil (15.8 g/cm3). The table compares the melting point, density and resistivity of these alloys using the supplier and specification figures.", "compare_rows": [ { "label": "Melting point, Au-Ni foil", "benchmark": "melting_point", "scope": "material" }, { "label": "Density, Au-Pd foil", "benchmark": "density", "scope": "material" }, { "label": "Electrical resistivity, Au-Ni foil", "benchmark": "electrical_resistivity", "scope": "material" } ], "handling": [ "Au-Ni and Au-Pd foil are supplied as rolled (Goodfellow temper). The supplier gives no hot-working data.", "Keep nickel-containing alloys away from skin that is sensitive to nickel. PubChem lists nickel as a skin sensitiser.", "Record the heat treatment of Au-Fe wire, because annealing changes its thermopower.", "The Au-Ni brazing filler is specified with a solidus-liquidus of 949 °C (AMS4787)." ], "good_for": [ "Oxidation-resistant contacts and microconnectors (Goodfellow, Au-Ni and Au-Pd).", "Brazing ceramics and refractory metals in packages at about 949 °C (AMS4787 Au-Ni filler).", "Thermocouples at very low temperature, where NBS found Au-Fe the most promising thermoelement (5 to 280 K)." ], "watch_out": [ "Most alloys here have only supplier figures. The Au-Ag and Au-Sb entries have almost no property data.", "Nickel in Au-Ni and white gold can cause skin allergy.", "Wire-to-wire scatter in Au-Fe thermocouples reached about 9% at 4 to 20 K in the NBS comparison." ], "verdict": "Gold alloys are chosen for oxidation-resistant contacts, brazes and thermocouples. The Au-Ni, Au-Pd and Au-Fe entries have usable data, while Au-Ag and Au-Sb are thin, and the nickel allergy risk should be handled in design.", "recipe": { "line": "Au82/Ni18 is gold and nickel in an 82 to 18 ratio, sold by the supplier as foil and spooled wire. Au75/Pd25 is gold and palladium in a 75 to 25 ratio. The Au-Fe thermocouple alloys contain 0.02 and 0.07 at% iron, and the Au-Sb eutectic is 24.8% antimony by weight.", "parts": [ { "name": "Gold", "symbol": "Au", "role": "Base metal. The supplier describes gold as resisting oxidation and carrying the electrical conduction in contacts." }, { "name": "Nickel", "symbol": "Ni", "role": "Alloying partner. Au82/Ni18 melts at 955 degC (supplier). Supplier notes trace platinum and yttrium improve sulfurization resistance." }, { "name": "Palladium", "symbol": "Pd", "role": "Hardness and wear resistance. The Au-Pd foil melts at 1410 degC." }, { "name": "Iron", "symbol": "Fe", "role": "Gives the Au-Fe alloy its thermoelectric behaviour at very low temperature." }, { "name": "Antimony", "symbol": "Sb", "role": "Forms the Au-Sb eutectic at 633 K. Other Au-Sb compositions were not read." } ] }, "risk_groups": [ { "title": "For people", "lead": "Gold on its own is classed as not hazardous in most company reports, but nickel in an alloy can cause skin allergy.", "points": [ { "label": "Nickel", "line": "PubChem lists the allergic-skin-reaction statement for nickel in 99.9% of company reports. Nickel is in Au-Ni and in most white gold." }, { "label": "Gold", "line": "Pure gold does not meet GHS hazard criteria in 99.2% (502 of 506) of company reports on PubChem." }, { "label": "Other alloys", "line": "No GHS classification was read for the Au-Pd, Au-Ag, Au-Fe or Au-Sb alloys." } ], "level": 0, "verdict": "Gold is not hazardous; nickel is a sensitiser" }, { "title": "Heating and brazing", "lead": "Au-Ni brazing filler melts at about 949 °C. Fume and flux hazards were not read in this run.", "points": [ { "label": "Solidus-liquidus", "line": "The AMS specification gives 949 °C (1740 F) for the 82Au-18Ni filler metal." }, { "label": "Joint", "line": "The brazing range is set by the alloy, so keep the joint below the melting point of the parts being joined." } ], "level": 1, "verdict": "Brazing near 949 °C; fumes not assessed" }, { "title": "Handling", "points": [ { "label": "Heat treatment", "line": "Annealing changes the thermopower of Au-Fe wire, so each wire needs its heat treatment recorded." }, { "label": "Foil", "line": "The Au75/Pd25 foil is 0.2 mm thick and supplied as rolled." } ] } ] }, "updated": "2026-10-26", "review": { "status": "draft", "method": "assistant", "checked_values": 13, "unreachable": 2, "caveats": 4, "note": "Written by an AI assistant on 2026-10-26. Au82/Ni18 values, Au75/Pd25 values, the AMS4787 solidus-liquidus, the Au-Sb eutectic row, the Au-Fe Seebeck values and the USGS shares were read from pages fetched in this run. Heraeus contact-grade pages returned 404 and the PGM chapter was not retrieved, so those are gaps. The Au82/Ni18 thermal conductivity disagrees between two supplier pages." }, "sources": { "goodfellow-au82ni18": { "title": "Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page", "id": "Goodfellow product page, Au 82 / Ni 18, foil as rolled", "url": "https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" }, "goodfellow-aunimaterial": { "title": "Goodfellow: Gold-Nickel alloy material information (Au82/Ni18)", "id": "Goodfellow resources page, gold-nickel material information", "url": "https://www.goodfellow.com/usa/resources/gold-nickel-alloy-material-information/", "year": 2026, "kind": "web", "license": "supplier web page, linked not reproduced" }, "goodfellow-au75pd25": { "title": "Goodfellow: Gold-Palladium alloy foil (Au75/Pd25) product page", "id": "Goodfellow product page, Au 75 / Pd 25, 0.2 mm foil", "url": "https://www.goodfellow.com/usa/gold-palladium-alloy-foil-au75-pd25-group", "year": 2026, "kind": "datasheet", "license": "supplier product page, linked not reproduced" }, "ams4787c": { "title": "AMS4787C: Brazing filler metal, high temperature 82Au-18Ni, 1740 F (949 C) solidus-liquidus temperature", "id": "SAE AMS4787 revision C, dated 4/1/1990", "url": "https://saemobilus.sae.org/content/AMS4787C", "year": 1990, "kind": "standard", "license": "SAE International, title and scope read, text not reproduced" }, "sparks1972": { "title": "Low Temperature Thermocouples: KP, normal silver and copper versus Au-0.02 at% Fe and Au-0.07 at% Fe", "id": "Sparks, L. L., J. Res. Natl. Bur. Stand. A 76A(3), 263-283, doi 10.6028/jres.076A.029", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6706574", "year": 1972, "kind": "paper", "license": "public domain (NBS)" }, "engtoolbox-gold": { "title": "Engineering ToolBox: Gold binary eutectic alloys and melting points", "id": "Engineering ToolBox, gold alloys melting points table (cited 2008 on page)", "url": "https://www.engineeringtoolbox.com/gold-alloys-melting-points-d_1434.html", "year": 2008, "kind": "web", "license": "web page, linked not reproduced" }, "usgs-gold": { "title": "Mineral Commodity Summaries 2026: Gold", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gold.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-nickel": { "title": "Mineral Commodity Summaries 2026: Nickel", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-silver": { "title": "Mineral Commodity Summaries 2026: Silver", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-antimony": { "title": "Mineral Commodity Summaries 2026: Antimony", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-antimony.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "pubchem-nickel": { "title": "PubChem compound record, Nickel (CID 935), GHS classification", "id": "CID 935", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Nickel", "year": 2026, "kind": "database", "license": "public domain (NCBI)" }, "pubchem-gold-ghs": { "title": "PubChem compound record, Gold (CID 23985), GHS classification", "id": "CID 23985", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/23985", "year": 2026, "kind": "database", "license": "public domain (NCBI)" }, "wiki-white-gold": { "title": "Wikipedia: White gold", "id": "en.wikipedia.org, White gold article", "url": "https://en.wikipedia.org/wiki/White_gold", "year": 2026, "kind": "web", "license": "CC BY-SA 4.0" }, "wiki-electrum": { "title": "Wikipedia: Electrum", "id": "en.wikipedia.org, Electrum article", "url": "https://en.wikipedia.org/wiki/Electrum", "year": 2026, "kind": "web", "license": "CC BY-SA 4.0" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/gold-alloys/" }